Glossary
Each HCP term in one line, from Harness Pack and Binding to Sense, land and the four faces, with a link to the page that explains it.
Use this table for quick lookup. The normative definitions live in §1 Terminology, and each row links to the page that covers the term in full.
| Term | One line | More |
|---|---|---|
| HCP | Harness Context Protocol: installs a capability into an agent harness as one pack with two loops | What is HCP |
| Harness | The environment an agent runs in: model, tools, memory, policy, runtime | Concepts |
| Harness Pack | Directory of surface.json, policy.json, HARNESS.md | Pack |
| Manifest | surface.json: identity, adapter, binding, commands, triggers | Manifest |
| Command | Named operation a pack exposes; wire name verb_key | Command |
verb_key | Wire identifier of a command (plan, setup.connect) | §3 |
| Twin face | A command's CLI form and JSON form produce the same result | §6.5 |
| Execute | Inbound loop: an Invoker runs a command | §6 |
| Sense | Outbound loop: a pack announces a world change | §7 |
| Trigger | Declared Sense event, stimulusTriggers[].ref | Triggers |
| Policy | Per command or trigger: operation, privacy.land, confirm | Policy |
| Operation | The effect class of a command, read or write | §4.3 |
| Land | The data domain a command touches: personal | brain | local | §4.4 |
| Confirm | Gate on writes, satisfied by args.confirm or args.apply | §4.5 |
| Access | The user's or operator's setting for which commands run without asking: mode, rules, approvals | Access |
| Access mode | manual | auto | run, how much runs without asking | Access |
| Approval view | The typed card a person sees when a command asks, built from the pack and the call's arguments | Access |
| Command title | The pack's words for a step, live while it runs and done after | Command |
| Binding | How a command gets credentials at exec time: mode and hub, never a secret | Binding |
| Mode | public | user | local | mothership | mock | §8.2 |
| Hub | Component kind that mints: keyring, local-credential, public, none | §8.3 |
| Family | Group of packs sharing one consent | §8.3 |
| Mint | The runtime gets a credential from the hub for one exec | §8.4 |
| Connect | Lifecycle step that establishes Binding; capability pack.connect | §8.5 |
| Principal | The acting identity: human, service, agent or mothership | Principal |
| Mothership | Operator or fleet identity; the Binding mode for control-plane packs | §8.2 |
| Tenant | Organisational scope from the session, never from args | §9.2 |
| Project | Sub-scope required for land brain | §9.2 |
| Capability | One of five grant axes | §9.4 |
| Grant | { capability, pack_id?, verb_keys? } held by a Principal | Authorization |
| Invoker | Who calls Execute: agent tool, API, UI, human CLI | Invoker |
| Adapter | How a command runs: wrap, composite, openapi, sense_only | Adapter |
| Wrap | Adapter that spawns wrap.bin with rendered argv | Wrap a CLI |
| Composite | In-process adapter | Adapter |
| Pass-through | Bootstrap-only whole-CLI wrap with allowed subcommands | §3.3 |
| Plane | runtime (user work) or control (operator lifecycle) | §2.5 |
| Runtime | Loads, authorises, binds, executes, routes Sense | Build runtimes |
| Reference runtime | createReferenceLocalRuntime in the SDK | SDK |
| Host | An agent product that adopts HCP | Adopt in hosts |
| Projection | A pack's view on a surface: CLI, host tool, Skill, MCP export | §12 |
| Four faces | Wire, CLI, host tool and Skill must name a command consistently | §12.4 |
| Skill | HARNESS.md, the teaching document for humans and agents | Skill |
| Lead | Text between the Skill title and first ##; the stable-context excerpt | §5.3 |
| Sandbox | Default exec posture: bin allow-list, cwd jail, no ambient credentials | §10 |
| Native-local | Explicit opt-out of the jail on a trusted machine | §10.3 |
| Availability | installed / activated / connected / executable | §11.2 |
| Store | $HCP_HOME, which holds packs, skills and state | CLI |
hcpx | The reference CLI's binary, also installed as hcp | Quickstart |
| Eval case | One expectation about a command in hcp.eval.json, run through the runtime by hcpx eval | Check and evaluate |
| Bootstrap pack | hcp-cli, which describes the runtime's own lifecycle | §11.4 |
| Gold pack | A reference pack that ships with the SDK (transit, ledger, echo) | Examples |
| Sink | Where Sense records land: inbox or silent | Sense delivery |
| Conformance vector | Executable test tied to a spec section | §14 |
| RFC | Change proposal to the protocol | RFC process |
| Agent Skills | External standard for teaching documents; HARNESS.md is compatible | Landscape |
| MCP | Model Context Protocol, a transport HCP can export to | Landscape |
| Connector | Not an HCP type; a vendor SDK inside a product runtime | Landscape |